This invention relates to tetrabenazine compounds (TBZ compounds) and methods for the preparation of said tetrabenazine compounds.
Since first reported on in 1957 (Pletscher, A. (1957) Release of 5-hydroxytryptamine by benzoquinolizine derivatives with sedative action, Science 126, 507), tetrabenazine and structurally related compounds have been widely investigated, and a number of TBZ compounds and derivatives of tetrabenazine have shown promise in the treatment of a variety of conditions affecting human health. For example, dihydrotetrabenazine has been identified as an agent for the treatment of schizophrenia and other psychoses (See for example WO 2007017654 A1), and tetrabenazine has shown promise as an agent in the treatment of Huntington's disease (Neurology (2006), 66(3), 366-372). Although most preparations used in biological studies of tetrabenazine and its derivatives have been carried out on racemates, in at least one instance the biological activity exhibited by enantiomers tested separately was highly differentiated (See Koeppe, R. A. et al. (1999) Assessment of extrastriatal vesicular monoamine transporter binding site density using stereoisomers of [11C]dihydrotetrabenazine, J Cereb Blood Flow Metab 19, 1376-1384).
Notwithstanding, the availability of tetrabenazine and derivatives of tetrabenazine in racemic and enantiomerically enriched forms, there is a need for improved synthetic methods which provide either or both enantiomers of tetrabenazine, derivatives of tetrabenazine, and analogs of tetrabenazine. In addition, there is a need to provide novel synthetic intermediate compositions which may be used to prepare either or both enantiomers of tetrabenazine, derivatives of tetrabenazine, and analogs of tetrabenazine.
The present invention provides both a new and efficient synthetic methodology which may be used to prepare either or both enantiomers of tetrabenazine, derivatives of tetrabenazine and analogs of tetrabenazine. In addition the present invention provides novel synthetic intermediate compositions which may be used to prepare either or both enantiomers of tetrabenazine, derivatives of tetrabenazine and analogs of tetrabenazine.